This invention relates to a novel agent for improving drainage of pulp slurry by adding the agent into the slurry.
In the paper making industry, various efforts have been made to increase the paper making rate thereby improving the productivity and lowering the production cost. For the reason, an agent for improving drainage of pulp slurry (pulp slurry drainage improver) has been widely used.
However a relationship between the increase of the paper making rate by use of the agent and the decrease of the formation on the dryer is quite delicate. Therefore a high level of techniques are required to improve the drainage of pulp slurry without impairing the uniformity of paper quality.
As the pulp slurry drainage improver, there has been used a highly polymerized polyethylene imine. However it has drawbacks that (1) in order to achieve desirable drainage, it is required to add it to pulp slurry in a relatively high amount and (2) it is rather toxic.